Many substances are used in the manufacture of foods intended for persons and animals that restrict their intake of carbohydrates or calories. Such substances generally should be of low caloric value and of a generally non-nutritive nature. In addition, such substances should not be toxic or unwholesome. Foods or animal feeds produced using such substances preferably are formulated such that they resemble higher calorie products in texture, taste and physical appearance.
Among such substances are synthetic sweeteners. When a synthetic sweetener such as saccharin or aspartame is used in a dietetic food as a substitute for sugar, the other physical properties which would have been imparted by sugar, such as appearance, bulk mass, and texture, may also be imparted to the dietetic food by a separate ingredient. For instance, because saccharin and aspartame both are substantially sweeter than sugar, it is desirable when providing these sweeteners in commercial form to provide a low-calorie, non-nutritive carrier so that the bulk mass, appearance, and texture of the added sweetener approximates that of sugar.
Many bulking agents are known in the art. One such bulking agent that is well known in literature is polydextrose, as is taught, for instance, in U.S. Pat. Nos. 3,766,165 and 3,876,794 (both to Rennhard). Polydextrose has a substantially reduced caloric value relative to sugar (about 1 Kcal/gm), or about 25% that of dextrose. As such, polydextrose may be used as a bulking agent in connection with synthetic sweeteners and other applications.
Although polydextrose is satisfactory for many purposes as a non-nutritive bulking agent, there exist several practical difficulties concerning the use of this material. For instance, the production of polydextrose is not without difficulty. Polydextrose generally is prepared in a condensation reaction that is performed under harsh conditions. As such, the condensation reaction often results in a dark colored product that has an undesirable acidic and bitter flavor. Numerous efforts have been made to address this problem. For instance, efforts to improve on the manufacturing process of polydextrose have been suggested. For instance, in EP 404,227 (to Cooperative Vereniging Suiker Unie V.A.) and in U.S. Pat. No. 5,015,500 (to Elmore), various extrusion techniques for polydextrose are purportedly taught. Another reference, U.S. Pat. No. 5,558,899 (to Kuzee et al), purports to disclose the production of polydextrose via use of microwave energy.
Other references purport to disclose methods to improve the taste or flavor of polydextrose. For instance, U.S. Pat. No. 4,622,253 (to Torres) purportedly teaches peroxide bleaching of polydextrose in an alcohol solvent. U.S. Pat. No. 4,948,596 (to Bunich et al.) purportedly discloses a liquid/liquid extraction process for purifying polydextrose. U.S. Pat. No. 4,956,458 (to Luo et al.) is said to disclose another process said to be useful for purifying polydextrose. U.S. Pat. No. 5,191,015 (to Bunich), U.S. Pat. No. 5,677,593 (to Guzek et al.), and U.S. Pat. No. 5,831,082 (to An et al.) purport to teach chromatographic methods for purifying polydextrose. U.S. Pat. No. 5,573,794 (to Duflot) purports to disclose glucose oxidase treatment of polydextrose followed by ion exchange chromatography. Finally, U.S. Pat. No. 5,601,863 (to Bordeo et al.) and U.S. Pat. No. 5,424,411 (to Duflot et al.) disclose hydrogenated polydextrose.
At least one prior method of obtaining resistant dextrins is described is U.S. Pat. No. 5,620,873. Generally, starches are heated with a small amount of strong acid, typically hydrochloric acid, to form a pyrodextrin, in what is known as a dextrinization reaction. The reaction consists of the decomposition of the starch by the acid to small molecular weight carbohydrates like glucose, followed by random re-polymerization of the low molecular weight carbohydrate products to form dextrins which have higher molecular weight. The pyrodextrins made are a mixture of mainly glucose polymers with mixed glycosidic linkages. The mixture of the pyrodextrins is then hydrolyzed with enzymes like alpha-amylase and/or glucoamylase to convert the enzyme-digestible fraction of the dextrin mixture to smaller molecules like glucoses and other oligosaccharides. By chromatographic fraction, the smaller molecules can be separated from the larger enzyme-digestion resistant dextrins. The resistant dextrins are considered as water soluble fiber, which have much higher value, while the smaller molecules like glucose have much lower value.
Another method for making a resistant type of dextrin is disclosed by U.S. Pat. No. 5,358,729. This reference is directed to a process of preparing indigestible polysaccharides by dextrinizing a starch with an inorganic acid like hydrochloric acid in an extruder at high temperature. However, according to the inventors, the products are “not adaptable to be employed as food material due to its “stimulative taste and smell, coloring difficulty, etc.”
The foregoing approaches to polydextrose production are somewhat limited in utility. For example, one principal drawback found in these approaches is that the polydextrose produced by any process typically includes substantial quantities of undesired color and flavor components, and substantial effort is required to reduce the levels of such components to acceptable levels. Moreover, the polydextrose product that is obtained in a typical condensation reaction has a low molecular weight. It would be desirable to have a low calorie bulking agent that has the properties of a higher molecular weight product such as a maltodextrin.
More recently, to address this latter concern, a number of patents, including U.S. Pat. No. 5,264,568 (to Yamada et al.), U.S. Pat. Nos. 5,358,729, 5,364,652 and 5,430,141 (all to Ohkuma et al.), and EP 368,451 (to Matsutani Chemical Industries Co. Ltd.) purport to disclose a product, commonly known as FIBERSOL®, that is formed by starch pyrodextrinization followed by enzymatic hydrolysis to leave an undigestive carbohydrate remnant. It is said that the disclosed product can be hydrogenated and/or ion exchanged to give a final product with reduced caloric content and soluble fiber benefits. This product is higher molecular weight than most polydextroses, and therefore has certain properties that rival maltodextrins. However, the product also suffers from low processing yields, significant processing complexities, and high final cost.
The inclusion of a food acceptable polyol such as sorbitol in the saccharide-carboxylic acid reaction mixtures prior to polycondensation function as internal plasticizers to reduce viscosity, minimize foaming, and also provide improved color and taste. In addition to sorbitol, other food-acceptable polyols including glycerol, erythritol, xylitol, mannitol and galactitol may be used. Although the use of polyols as plasticizers has been successful in aiding processability, consumers are increasingly objecting to their use in foods. In addition some of the polyols some have shown adverse effects including not being well tolerated by the human metabolic system.